题解 | #牛牛学数列#
牛牛学数列
https://www.nowcoder.com/practice/0b97367cd2184c12a0e02f7c223aee11
#include<stdio.h>
int main()
{
int n,i,sum=0,j;//j用来变符号
scanf("%d",&n);//输入整数n
for(i=1;i<=n;i++)//i累加到n
{
j=(i%2==0?-1*i:i);//当i为偶数，j等于i乘-1，当i为奇数，j等于i
sum=sum+j;//sum累加会变号的j
}
printf("%d",sum);//输出sum
return 0;
}
